Reported willingness to participate in a hypothetical HIV vaccine trial and its translation to actual participation among healthy adults—Experience from Kenya

Objective To evaluate initial reported willingness to participate in a hypothetical HIV vaccine clinical trial and actual participation of volunteers in a longitudinal observational study. Methods We recruited HIV negative male and female volunteers aged 18–45 years into a longitudinal observational study at KAVI–ICR Kangemi in Kenya, to serve as a pool from which to draw participants into a phase I HIV vaccine clinical trial. A structured questionnaire was used to collect information regarding willingness to join a HIV vaccine clinical trial in the future. Study follow-up visits were every 6 months. Results A total of 105 participants were screened and 100 (M46:F54) were enrolled into the observational study. Ninety- four per cent of those enrolled expressed willingness to participate in a future HIV vaccine trial. Altruism and desire to learn the body’s response to the vaccine were the most motivating factors at 40% and 25% respectively. At the onset of a 40-person phase I HIV vaccine trial, 86 observational study participants who had previously expressed willingness to participate were contacted but only 26 (30%) came for information. All 26 consented to participate and after screening for eligibility, 24 were eligible. Of the 24, 15 were enrolled. These numbers were not adequate; hence the vaccine trial employed other recruitment methods to meet the deficit. Conclusion Observational “pools” of cohorts may not provide adequate number of participants into vaccine clinical trials even if they report willingness; therefore supplementary recruitment methods such as direct community recruitment, passive approach, and snowballing need to be in place.